Monitoring living cell assays with bio-impedance sensors

This work proposes a cell–microelectrode model to be used on cell culture assays as an alternative to end-point protocols employed in cell growth and cell biometry applications. The microelectrode model proposed is based on the area overlap between the microelectrode sensor and the living cells as main parameter. This model can be applied to cell size identification, cell count, and their extension to cell growth, motility and dosimetry protocols. A procedure to fit the proposed model to microelectrode electrical performance is presented, enabling the decoding of empirical measurements and its interpretation in terms of number of cells. This fitting procedure depends on three parameters: microelectrode geometry, gap resistance between substrate attached cells and microelectrode and, mainly, on microelectrode area covered by cells. The model has been implemented employing Analog Hardware Descriptions Language (AHDL) to be incorporated also to mixed-mode simulation processes during circuit design flow. ments performed with commercial electrodes are described, illustrating a procedure to obtain cell number in real time in both, growth and dosimetry assays, employing an established cell line (AA8). The results are displayed in the form of growth curves (cells were growing during a week), as well as dosimetric response after treatment with MG132, a proteasome inhibitor. The results agree with the expected performances, with errors around 10–20% in the number of cells measured, therefore we think that these results are promising.